The overall scientific goal of this project is to contribute to our knowledge of the attachment of coaggregation-specifc carbohydrate to the surfaces of oral bacteria. In Year 05, we will continue to study the lactose-inhibitable specific coaqgregation of Streptococcus sanguis strain 34 (Ss34) with Actinomyces viscosus strain T14V(T14V), an importnt oral pathogen. This coaggregation system, which serves as a model for dental plaque formation, involves a heat-labile agglutinogen on surface fibrils of T14V and a heat-stable carbohydrate receptor on the surface of Ss34. Two main approaches will be employed: SPECIFIC AIM 1. Determine the chemical composition and, possibly, the structure of, the linkage unit that connects the carbohydrate receptor of Ss34 to the insoluble peptidoglycan matrix of the cell wall. SPECIFIC AIM 2. Determine, if possible, the requirement table for the biosynthesis of carbohydrate receptor and/or its linkage unit. Achievement of these aims will be attempted by investigation of electrophoretically purified cell wall preparations and of membrane and membrane/wall enzyme preparations isolated from cell homogenates. Cell walls will be specifically (enzymatically) or selectively (chemically) degraded, fractionated, and subjected to chemical analysis after borohydride reduction. In the former case, receptor will be isolated while still attached to peptidoglycan fragments. In the latter case, the site of acid-labile glycosidic and phosphodiester linkages will be determined. Comparison of these data will enable generation of structural models for carbohydrate receptor and linkage group. The synthesis in vitro of polymers from appropriate combinations of radioactive nucleotide sugars will be sought. It is hoped that the information gained from the complementary approaches of chemical and enzymatic analyses will at least permit establishment of reasonable models for attachment of carbohydrate receptor to peptidoglycan.